The toxicity of mercury is such that the element should not be allowed to contaminate air and water. Spilled mercury is often the source of mercury poisoning because it is finely divided and produces a relatively large amount of mercury vapor. Moreover, collecting all the spilled mercury in any particular spill is extremely difficult because of the high surface tension and high density of liquid elemental mercury.
Heretofore, granulated active charcoal containing iodine has been considered to be the best means of removing mercury vapor. However, the absorption rate and capacity of iodine bearing carbon for mercury is relatively low. More recently it has been proposed to employ a water soluble silver salt impregnated on a solid carrier and containing sufficient moisture for speedy reaction of the silver salt with mercury. This latter method, however, is not without its disadvantages and is unduly costly and requires an undue reaction time.
Still more recently a significant advance in the art was made with the discovery of a composition that was capable of taking up elemental mercury at a relatively fast rate and at a cost not prohibitively expensive. Said composition, as disclosed in U.S. Pat. No. 3,975,298 issued Aug. 17, 1976 to J. T. Baker Chemical Company as the assignee of J. W. Seidenberger, comprises a composition composed of a granular metal, a metal powder and a non-hydroscopic solid acid. This novel composition has not, however, been entirely useful or practical in all situations, such as, for example, where the liquid mercury has been spilled on vertical or irregular surfaces, that is, other than on smooth horizontal surfaces. Moreover, physical removal of the resulting paste from the spill area has not been entirely satisfactory and the use of the composition of said patent can result in further contamination of the spill area by contamination thereof with the metal powder or granules. Another disadvantage is that the resulting paste, even if recovered from the spill area does not lend itself to easy reclamation of the liquid mercury from the paste. In fact, recovery of the liquid mercury is essentially impossible or extremely impossible in most instances.
There is, therefore, a need for a method whereby spilled liquid elemental mercury can be collected and the problems mentioned in the preceding paragraph eliminated or substantially reduced.